chicago



53 weight material. I am not aware that any- Reissued Sept. 27, 1932 UNITED STATES PATENT OFFICE RICHARD ERICSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO UNITED STATES GYPSUM: C0,,

OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS I LIGHT-WEIGHT CERAMIC MATERI KL AND PROCESS OF MAKING THE No Drawing. Original. No. 1,702,076, dated February 12, 1929, Serial No. 226,259, filed October I4, 1927.

Reissue No. 17,523, dated December 17, 1929 Serial No. 899,098, filed October 11, 1929. This application for reissue filed June 3, 1932. Serial No. 615,284.

This invention relates to a porous and light-weight cellular ceramic product, and a method for producing and manufacturing the same commercially. One of the objects of the present invention is to produce a light-weight burned ceramic product, suitable for structural and other uses, consisting of a body of ceramic material having interspersed therein a very large number of substantially uniform voids so as to render the product highly cellular, this being accomplished by incorporating with a ceramic argillaceous earthy material, while in admixture with water, a foam sufficiently tenacious to maintain itself Without brealnng down during the shaping or casting of the material.

A further object of the invention is to mix argillaceous material that has previously been mixed with water with suflicient of a gaseous density-reducing agent or medium so as greatly to extend the same in volume, and to pour the resultant foamy mass into suitable molds in the presence of a substance capable of causing the mass to set up sufilcientl rapidly to entrap, and to retain entrappe I the incorporated foam or gaseous densityreducing agent; then to dry the form thus 9 produced, and subsequently to burn the same to form a hardened cellular ceramic product having substantially a foam-like structure.

A further object of the invention is to incorporate a tenacious foam with a clay slip and a reagent capable of causing the superficial setting up-of the slip so asto entrap the bubbles of said foam to form an extended mass of ceramic material of a structure substantially like that of the foam added, and subsequently to dry and burn said mass to produce a cellular ceramic material of foamlike structure.

Other objects of the invention will appear from the description and claims hereinbelow.

The use of foam or other density-reducing substance in connection with cementitious materials to form-porous cellular compositions when set and hardened to their final state with water, is becoming established as one commercial means of producing a lightthing ofthis principle has been applied to the production of ceramic materials where an argillaceous, earthy material is given a porous cellular structure by admixture with a tenacious foam-producing agent and subsequently this porous argillaceous material is heat-treated to render its cellular structure fixed in a finished ceramic product.

A comparatively light porous material suitable for structural purposes or suitable as a heat insulator can be made from clay or other argillaceous earthy material by firstforming a plastic mixture of the earthy material with water, then mixing in a previously prepared tenacious foam or .other density-reducing agent to uniform admixture, next forming I the mass into a cast or shaped product of any desired form, then drying this cast to pre- Y serve its cell structure, and finally baking or burning this dried cast until a hardened mass results which retains permanently fixed the porous" cellular structure afforded by the foam addition.

- In'carrying on my invention I can use the ordinary earthy materials such as clay, shale, etc. generally used as raw materials for producing ceramic products. Also these may be augmented with other special substancec like flint, feldspar, grog, etc. for specific properties as needed, either during some step in the manufacturing or in the final product. These raw materials are reduced to the desired state of fineness by suitable disintegrating. or grinding means, and rendered lastic 'with' water. However, in my process reduce to perhaps a more fluidly lastic state than is the ordinary practice in the production of common ceramic products such as brick or tile. This is usually necessary commercial plaster retarder, glue, soap, resin greater opportunity for shrinking and soap, and various admixtures of these, etc. The foam itself may be made by' beat1 ng the water solution of these materials V10- lently' or by introducing a current of air into the solution with agitation, or by any other means of suitably producing such a foam. The greater the tenacity of the foa m, the better is itapplicable in carrying out the present invention.

J In the production of light-weight shale brick, I take shale as used in the manufacture. of ordinary brick and tile and, grind it sorthat it can be readily mixed with water.

sufficient water is then mixed with it to form aplastic mass of such consistency or fluidity that foam can readily be mixed therewith. With certain sha-les I have used, this is about six-tenths of one part of water by weight to one part of ground shale. The foam used is made by dispersing air into a solution composed of three-quarters of one part of powdered soap bark suspended in one hundred parts of water, and this foam burned at about the temperature and method used in burning the ordinary brick or tile products made from the same shale, care being taken not to fuse or melt the product during the burning or firing stage. After the, burning, the hard porous product is ready for use in a variety of ways. If the original shape of the cast was a brick, this finished porousv brick is then available as an insulating backing-up brick inhigh temperature insulation work. Or the burned prod- 'uct may be crushed and sized to form an aggregate for use together with a cementing material to yield a moulded and .cast structure. One use-of this crushed product is as a light-weight aggregate in the production of Portland, cement concrete.

. I have noticed in some cases where ex: tremely light-weight products (25-30 pounds per cubic foot density) are desired that these foam clay casts when dried exhibit some cracking and shrinking. This, of course, depends somewhat on the nature of the clay or shale used as a base, and is what is ordinarily experienced in the generalmanufacture of ceramic products. But in my light-weight foam process, the natural tendency of the clay or shale in this direction is, of course, augmented, .because after the-'foam addition the composite mix is less dense and consequently somewhat fragile. Thus, there is cracking during drying to manifest itself. I If the finished ceramic products are to be used as crushed aggregates this of course is immaterial, but if the finished porous lightweight ceramic product is to be used intact itself for structural purposes and thus must retain the form and size in which it was grog, and other coarser body materials is useful in this capacity.

cined' gypsum or plaster of Paris, which sets rapidly with water, will hardenthe cellular clay mass sufficiently to withstand the shrinking effect induced by' subsequent drying. The calcined gypsum, mixed with water, may be added to the mixture of argillaceous material and foam with good results. Accelerating the set of the calcined gypsum decreases the time required before the subsequent mixture stifi'ens. However, when gypsum is used, more care must be taken in burning the dried porous product be- 1 cause usually the fusing or melting point of .such a mixture is lowered the gypsum.

Many modifications of this invention will suggest themselves and I do not wish to be I have also found that a mixture of calby the addition of limited in various applications of this principle,- for the various modifications that. suggest themselyes do not depart from the spirit of this invention. Other typesof argillaceous material other than the natural earthy materials used may suggest themselves such as builtartificial refractory raw materials made p lastic by only small additions of clays or shales; and many types of foam or other density-reducing agents with greater or less stability than the soap bark foam cited may be used Also other methods of drying and burning may be 'used than merel preparing unit casts, and then drying and burning the same. For example, the casts may be partially dried and then placed in a rotary kiln where they can be furtherdried and burned in one operation,'if the material is intended forfuse primarily as an aggregate.

Having thus described my invention, what I claim is:

1. A porous ceramic material comprising the burned product resulting from heattreat-. ing a mixture of foam and argillaceous material.

.2. A porous light-weight ceramic product comprising burned argillaceous material madeporous by foam addition hile plastic.

3. A lightweight structural material comprising theflbnrned product resulting from heat-treatin 'argillaceous material in which a tenacious cam is incorporated prior to drying and burning.

4. A. porous light-weight material comprising the burned product resulting from heat-treating a mixture of argillaceous substance, tenacious foam, and substances adapted to prevent excessive shrinking and cracking during drying.

5. A light-weight ceramic material comprising the burned product resulting from heat-treating a mixture of argillaceous material, foam, calcined gypsum, and water.

6. A porous ceramic material comprising the burned product resulting from heat-treating a mixture of one part by volume of a plastic mixture 0 argillaceous material and water, with five parts of tenacious foam.

7. A cellular ceramic product comprising the burned product resulting from heat-treatinga mixture of one part by volume of a plastic mix of argillaceous material and water, four parts of tenacious foam, and onethird part ofcalcined gypsum.

8. The process of manufacturing a porous product comprising forming a fluid plastic mixture of finely divided argillaceous material with water, incorporating therein a tenacious foam, shaping and drying this admixture and finally heat-treating the dried porous mass to obtain a substantially hardened cellular product.

9. The process of manufacturing a porous ceramic material comprising the incorporation of tenacious foam into a fluid plastic mixtureofargillaceou's substance and water, the foam .volume being in excess of the volume of argillaceous water mixture used, casting this resultant mixture into desired shape, drying, and finally burning the dried porous mass at a temperature below its fusion point to maintain its porous structure throughout the burning process. I

10. The process of manufacturing a porous ceramic product comprising adding to a plastic mixture of argillaceous substance, foam density-reducing agent and water and calcined gypsum to prevent shrinkage during subsequent moisture loss, drying this composite mixture, and finally heat-treating the dry porous mass at a temperature below its fusion point to yield a hardened, porous product.

'16. The process of producing a light weight burned ceramic product which comprises mixing an argillaceous material with Water to form a slip, adding a substance thereto to cause the slip to assume a cellular structure, adding substances thereto capable of preventing shrinking and drying thereof,

- shaping the slip into form, and drying and burning the said form.

17. The process of producing a lightweight burned ceramic product which comprises mixing an argillaceous material with water, rendering the resulting mixture cellular by the incorporation of gaseous bubbles therewith, adding a reagent tosaid treated mixture to prevent collapse and shrinkage of the mixture, shaping and burning the dried product.

18. The process of producing a lightweight burned ceramic product which comprises mixing an argillaceous material with water, rendering the resulting mixture cellular by the incorporation of gaseous bubbles therewith,,adding calcium sulphate to the thus treated mixture, shaping the mixture and water, calcined gypsum to prevent into form, and drying and burning said shrinkage during subsequent moisture loss, drying this composite mass, and finally heattreating the dried porous mass at a temperature below its fusion point to yield a hardened porous product.

11. A light-Weight structural material comprising" the burned product resulting from heat-treating argillaceous material in which a density-reducing agent is incorporated prior to drying and burning.

12. A porous light-weight material comprising the burned product resulting from heat-treating a mixture of argillaceous substance, a density-reducing agent, and substances adapted to prevent excessive shrinking and cracking during drying.

13., A light-weight ceramic material comprising the burned product resulting from heat-treating a mixture of argillaceous material, a density-reducing agent and calcined gypsum. I

14. The process of manufacturlng a porous 19-. The process of manufacturing a cellular ceramic product which comprises forming a plastic mixture ofv an argillaceous substance and water, incorporating air bubbles therewith, vent shrinkage during subsequent loss of moisture from the thus produced foamy mass, foaming said mass into shape, drying the shaped mass, and burning the same at a temperature below its fusion point to yield a hardened product.

20. A porous lightweight material. comprising the burned product resulting from heat-treating a mixture of argillaceous materials, a gaseous density-reducing agent, and substances adapted to. prevent excessive shrinking and cracking during the drying.

21. A light-weight ceramic material com prising the burned product resulting from heat-treating a mixture of argillaceous mateand drying the same,

adding calcium sulphate to pre.

I gypsum.

rial, a gaseous density-reducing agent, and

22. A porous light-weight ceramic product consisting of argillaceous material and calcium sulphate, having a structure.

23. Aporous 1i ht-weight ceramic product consisting of argi aceous material, and a substance vcapable of preventing the shrinking and cracking thereof, the product being characterized by having a foam-like cellular structure.

24. A light-weight ceramic product containing argillaceous material, a substance foam-like cellular adapted to prevent shrinking and cracking "thereof, and permanently fixed voids in foam-like formation.

25. A light-weight ceramic product containing 'argillaceous' material, calcium sulphate, and permanently fixed voids'in foamlike formation.

In witness whereof, I have hereunto subscribed myname this 28th day of May, 1932.

RICHARD ERICSON. 

